Using liquid polymer clay to create icing and other types of topping including sauces is a lot of hard work but the end results are fantastic.
The technique I use is with a small plate and the back of a spoon and then store any excess clay in a little air tight pot for use later. I use Translucent Liquid Sculpey for this.
First of all condition some normal clay (soft is better than classic as it will condition quicker). Then break it up into small pieces, squeeze out some liquid clay and then add the small well-conditioned pieces of clay to your plate (this is where the hard work comes in) and start mixing it with the back of the spoon. You can keep adding small pieces of clay and more liquid clay as you mix it, I like to mix quite a bit then I have lots left for next time I need some.
This can then be used for various things liking icing cupcakes of giving a realistic look to blood that you want to stick in certain places like a knife or on the ends of something severed.
You can use any colour clay you like and once you have mixed enough you will need to add a small amount of oil paint to make the colour really pop (do this even if you are mixing white).
You can’t just use anything to colour the liquid clay but you can use quite I few things. DON'T use acrylic paint it does crazy stuff in the oven and will leave your icing looking like curdled milk. The best thing to use in oil paints but in tiny amounts till you get the colour you want. You can use oil pastels, soft pastel, mica powders; the best by far is oil paints.
If however you want your liquid clay to be translucent then use Fimo deco gel. It bakes a lot clearer than the liquid Sculpey and makes for a better sauce or translucent blood. You don’t need to add any solid clay to this just squeeze out the amount you need and mix small amounts of oil paint until you get the colour you require.
You can then add this to your creations before you bake them. However you need to remember that this will run and could end up in places you didn’t want it, so place it to the top of you make and then bake them straight away. The clay will begin to bake and run at the same time in the oven and hopefully run exactly where you want it. But if you think about it sauce is a very random pattern when you pour the real stuff, so the more random the clay sauce runs the better the look of your cake, ice cream or whatever you add it too.